/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/****************************************************************************
 * fs/vfs/fs_fdopen.c
 *
 *   Copyright (C) 2007-2014 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <tinyara/config.h>

#include <stdio.h>
#include <string.h>
#include <semaphore.h>
#include <fcntl.h>
#include <errno.h>

#include <tinyara/kmalloc.h>
#include <tinyara/fs/fs.h>
#include <tinyara/net/net.h>

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: fs_checkfd
 *
 * Description:
 *   Check if the file descriptor is valid for the provided TCB and if it
 *   supports the requested access.
 *
 ****************************************************************************/

#if CONFIG_NFILE_DESCRIPTORS > 0
static inline int fs_checkfd(FAR struct tcb_s *tcb, int fd, int oflags)
{
	FAR struct file *filep;
	FAR struct inode *inode;
	int ret;

	DEBUGASSERT(tcb && tcb->group);

	/* Get the file structure corresponding to the file descriptor. */

	ret = fs_getfilep(fd, &filep);
	if (ret < 0) {
		return ret;
	}

	/* Get the inode associated with the file descriptor.  This should
	 * normally be the case if fd >= 0.  But not in the case where the
	 * called attempts to explicitly stdin with fdopen(0) but stdin has
	 * been closed.
	 */

	inode = filep->f_inode;
	if (!inode) {
		/* No inode -- descriptor does not correspond to an open file */

		return -ENOENT;
	}

	/* Make sure that the inode supports the requested access.  In
	 * the case of fdopen, we are not actually creating the file -- in
	 * particular w and w+ do not truncate the file and any files have
	 * already been created.
	 */

	if (inode_checkflags(inode, oflags) != OK) {
		/* Cannot support the requested access */

		return -EACCES;
	}

	/* Looks good to me */

	return OK;
}
#endif

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: fs_fdopen
 *
 * Description:
 *   This function does the core operations for fopen and fdopen.
 *
 ****************************************************************************/

FAR struct file_struct *fs_fdopen(int fd, int oflags, FAR struct tcb_s *tcb)
{
	FAR struct streamlist *slist;
	FAR FILE *stream;
	int err = OK;
	int ret;
	int i;

	/* Check input parameters */

	if (fd < 0) {
		err = EBADF;
		goto errout;
	}

	/* A NULL TCB pointer means to use this threads TCB.  This is a little
	 * hack the let's this function be called from user-space (via a syscall)
	 * without having access to the TCB.
	 */

	if (!tcb) {
		tcb = sched_self();
	}

	DEBUGASSERT(tcb && tcb->group);

	/* Verify that this is a valid file/socket descriptor and that the
	 * requested access can be support.
	 *
	 * Is this fd in the range of valid file descriptors?  Socket descriptors
	 * lie in a different range.
	 */

#if CONFIG_NFILE_DESCRIPTORS > 0
	if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS)
#endif
	{
		/* No.. If networking is enabled then this might be a socket
		 * descriptor.
		 */

#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
		ret = net_checksd(fd, oflags);
#else
		/* No networking... it is just a bad descriptor */

		err = EBADF;
		goto errout;
#endif
	}

	/* The descriptor is in a valid range to file descriptor... perform some more checks */

#if CONFIG_NFILE_DESCRIPTORS > 0
	else {
		ret = fs_checkfd(tcb, fd, oflags);
	}
#endif

	/* Do we have a good descriptor of some sort? */

	if (ret < 0) {
		/* No... return the reported error */

		err = -ret;
		goto errout;
	}

	/* Get the stream list from the TCB */

#if (defined(CONFIG_BUILD_PROTECTED) || defined(CONFIG_BUILD_KERNEL)) && \
	 defined(CONFIG_MM_KERNEL_HEAP)
	slist = tcb->group->tg_streamlist;
#else
	slist = &tcb->group->tg_streamlist;
#endif

	/* Find an unallocated FILE structure in the stream list */

	ret = sem_wait(&slist->sl_sem);
	if (ret != OK) {
		goto errout_with_errno;
	}

	for (i = 0; i < CONFIG_NFILE_STREAMS; i++) {
		stream = &slist->sl_streams[i];
		if (stream->fs_fd < 0) {
#if CONFIG_STDIO_BUFFER_SIZE > 0
			/* Initialize the semaphore the manages access to the buffer */

			(void)sem_init(&stream->fs_sem, 0, 1);

			/* Allocate the IO buffer at the appropriate privilege level for
			 * the group.
			 */

			stream->fs_bufstart = group_malloc(tcb->group, CONFIG_STDIO_BUFFER_SIZE);

			if (!stream->fs_bufstart) {
				err = ENOMEM;
				goto errout_with_sem;
			}

			/* Set up pointers */

			stream->fs_bufend = &stream->fs_bufstart[CONFIG_STDIO_BUFFER_SIZE];
			stream->fs_bufpos = stream->fs_bufstart;
			stream->fs_bufread = stream->fs_bufstart;
#endif
			/* Save the file description and open flags.  Setting the
			 * file descriptor locks this stream.
			 */

			stream->fs_fd = fd;
			stream->fs_oflags = (uint16_t)oflags;

			sem_post(&slist->sl_sem);
			return stream;
		}
	}

	/* No free stream available.. report ENFILE */

	err = ENFILE;

#if CONFIG_STDIO_BUFFER_SIZE > 0
errout_with_sem:
#endif
	sem_post(&slist->sl_sem);

errout:
	set_errno(err);
errout_with_errno:
	return NULL;
}
